A known inkjet printing system has a maintenance unit. The maintenance unit comprises a wiping element configured to occasionally or regularly wipe an orifice surface of an inkjet print head. Such wiping is performed to remove an excess amount of ink, any dirt and/or any other material present on the orifice surface that may disturb accurate droplet ejection from the print head.
Other maintenance methods are also known from the prior art. Such known methods include methods in which (I) a cleaning fluid is provided on the orifice surface for loosening debris and then removing the fluid by wiping, brushing and/or suction and/or (II) ink is purged and the purged ink is received in a waste container, possibly using suction to receive the ink.
A disadvantage of the known printing system is the lack of control of the maintenance unit. If the maintenance unit fails and does not clean the orifice surface as expected, the accuracy of the droplet ejection may deteriorate and the droplet ejection may even fail completely. Thus, a print quality of the printing system deteriorates and a service technician may need to service the printing system. Since the print head is failing, the service technician will replace the print head instead of the maintenance unit that is causing the failure of the print head. As a consequence, the new print head will fail again soon after the replacement, since the maintenance unit is still not cleaning accurately.
Thus, it is desirable to be able to determine the performance of the maintenance unit such that a failing maintenance unit may be detected, preferably even before the accuracy of the droplet ejection starts to deteriorate significantly.